drm/ttm: Add some powerpc cache flush code.

Optimise the powerpc flushing path for TTM.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ttm/ttm_tt.c

@@ -68,7 +68,7 @@ static void ttm_tt_cache_flush_clflush(struct page *pages[],
 		ttm_tt_clflush_page(*pages++);
 	mb();
 }
-#else
+#elif !defined(__powerpc__)
 static void ttm_tt_ipi_handler(void *null)
 {
 	;
@@ -83,6 +83,15 @@ void ttm_tt_cache_flush(struct page *pages[], unsigned long num_pages)
 		ttm_tt_cache_flush_clflush(pages, num_pages);
 		return;
 	}
+#elif defined(__powerpc__)
+	unsigned long i;
+
+	for (i = 0; i < num_pages; ++i) {
+		if (pages[i]) {
+			unsigned long start = (unsigned long)page_address(pages[i]);
+			flush_dcache_range(start, start + PAGE_SIZE);
+		}
+	}
 #else
 	if (on_each_cpu(ttm_tt_ipi_handler, NULL, 1) != 0)
 		printk(KERN_ERR TTM_PFX